Method of manufacturing sheet packing material



Sept. 5, 1933. RoBERTs 1,925,206

METHOD OF MANUFACTURING SHEET PACKING MATERIAL Filed Sept. 29, 1950 INVENTOR. Y Eva/MED 190552725 hwa ATTORNEYS.

Patented Sept. 5, 1933 UNITED STATES METHOD OF lVIANUFACTURING SHEET PACKING MATERIAL Richard Roberts, Pasadena, Calif., assignor of one-third to Hans Giese, Santa Barbara,

Calif.

Application September 29, 1930 Serial No. 485,241

6 Claims. (Cl. 1542) My invention relates to a method of manufacturing sheet packing material, and has for its object the provision of a method wherein the manufacture of said material can be carried'on expedi tiously and cheaply, and in such manner that the resulting product will possess great heat-resisting qualities and will have maximum tensile strength.

An essential feature of the invention resides in the step of progressively building up a packing sheet of suitable thickness from a web of moist asbestos fibres, while simultaneously impregnating the web uniformly with latex, and also while pressing spirally wound portions of the web firmly together in order that the finished sheet may be of a homogeneous character, made up of laminations of asbestos fibres and interposed large quantities of latex.

In the drawing,

The figure is a diagrammatic illustration of such portion of an apparatus as has been found useful in the practice of the invention.

In carrying the invention intopractice'use is made of a horizontal traveling wire strainer or sieve 5, which operates over the small rolls 6, one or more of which may be driven uniformly in any suitable well-known manner. This strainer or sieve may be of any suitable well-known construction'that will permit much of the water in the pre-prepared pulp to pass through its meshes as the sieve travels in the direction of the coacting press rolls 7,7. These press rolls are located at a point immediately in advance of what I term the discharge end of the traveling sieve 5, and same are intended to be, respectively, driven in opposite directions, so that a moist web of asbestos fibres will be pulled through the rolls and compressed into a thickness generally about 1/250 of an inch. The web is thus acted upon by the rolls so as to express therefrom further quantities of the contained water. The front end of the web is then taken between a presser roll 8 and a large co-acting superposed cylinder 9, the latter arranged in rolling contact normally with the former. The said roll 8 functions to firmly press the web of moist asbestos fibres against the peripheral surface of the large cylinder 9 so that as the latter revolves laminations, so to speak, or wound portions of the web will be successively built up and pressed into intimate contact with each other. The step of feeding the pulp between the roll 8 and the large co-acting cylinder 9 may be continued until a sheet of the desired thickness has been produced, after which the entire mechanism is thrown out of operation and the manufactured sheet removed from the aforementioned large cylinder 9. The removal of the sheet is subject, however, to further treatment of the web during the act of superposing wound portions of the moist web of asbestos fibre. This subsequent treatment, which is necessary to the production of commercial packing material, will be described presently.

I have so far made reference to a form of mech-' anism for spirally laying a web or moist film of asbestos pulp upon a large cylinder so that the commercial sheet is virtually characterized by many laminations, so pressed together that the sheet is of a homogeneous nature. An essential feature of the invention resides in a novel and effective means for impregnating the still moist asbestos fibres with large quantities of latex, progressively with the step of laying the laminations of pulp upon the cylinder 9. To best accomplish this end of the invention, I employ a reservoir or receptacle 10 having a well 11 for the accommodation of a quantity of latex. A transferring roll 12 extends partly into the reservoir or receptacle 10 and, as illustrated, a portion of the roll is exposed from the receptacle and is arranged in normal frictional contact with the peripheral surface of the large cylinder 9. In this manner, the roll 12 functions as an applicator or transferring device, whereby uniform portions of latex are presented against the moist asbestos fibres as same are laid upon said cylinder. Thelatex, therefore, becomes thoroughly interspersed among the fibres of asbestos and perfect impregnation of the latter'is accomplished so that the finished commercial sheet, when produced of the desired thickness, is homogeneous and possessed of great tensile strength.

While I have described one means for progressively building up a sheet of predetermined thickness, the same consisting in the step of spirally training a web of moist asbestos fibres around a large cylinder, I do not wish to be limited in this respect. I am principally concerned with the idea of continuously subjecting a partly moist web of asbestos fibres'to an action that will result in the progressive creation of a packing sheet of predetermined thickness. Therefore,- the illustration is but an example of one known means for accomplishing the principal object of the invention. Neither am I concerned with the form of apparatus to be employed for conveying pretreated asbestos fibres to the traveling sieve 5. However, it is here stated that best results have been produced by first crushing and cleaning crude asbestos, then subjecting the same to the action of a suitable beating engine, while the is such that it is non-porous.

asbestos is in the presence of large quantities of water. This beating of the crushed asbestos is continued over such period until the asbestos has been reduced to a finely divided pulp. The pulp thus produced is now continuously beaten together with water, so as to cause even distribution of fibres in the water. The mechanism, which as I have stated above may be of any obvious character for pouring or transferring quantities of the pre-treated fibrous mass upon the endless sieve, may consist of a set of traveling scoops or buckets which progressively dip into the vat containing the fibrous mass which functions to cause the mass to be continuously poured onto a table 13 from which the mass discharges onto the top lid of the said sieve 5. Here it should be noted that the sieve 5 is in motion so that the web to.be entwined about the cylinder 9 will be fed in a direction to be taken up between the rolls 7,7. During the time in which the web travels from the table 13 to the point between the rolls 7,7, much of the moisture contained in the asbestos fibres passes therefrom and falls through the meshes of said sieve where it may be taken either to a sump or discharged back into the vat whence it came.

I have now set forth substantially all of the essential steps necessary to the preparation of my improved form of packing material, and it only remains to describe those steps which I find best to employ after a sheet of intended thickness has been built upon the surface of the cylinder 9. Assuming that the strip has been fully prepared upon the cylinder, I first idle the entire mechanism until the cylinder 9 is at rest. I then cut through the material as it has been laid upon the roll, taking the course of the length of the cylinder, and cutting entirely through the material. It is then free to be pulled off of the cylinder in perfect sheet. formation. The sheet thus taken from the cylinder is now subjected to the action of a hydraulic press so as to firmly compress the fibrous mass of matter and establish a perfect bond between the fibres and the latex. I then introduce the sheet to the effect of a drying heat, the temperature of which shall be sufficient to remove all remaining moisture. The sheet thus dried is then subjected to further action of a hydraulic press, or same may be run through calenders whereupon the sheet will be fully prepared and ready for the market.

I find that by applying latex to a moist web of asbestos fibres, the fibres very readily absorb large quantities of the latex, and incident thereto I am able to effect very complete impregnation of the structure. I also find that by the step of progressively building up the sheet by virtually piling up laminations or portions of a web and simultaneously therewith causing continuous saturation of the fibres with latex, I have produced a sheet of high heat-resisting qualities and of great tensile strength and one which is perfectly homogeneous and lacking in cellular construction. In other words, the texture of the material Another important feature resides in the fact that no heats are necessary except the final drying heat herein referred to.

The several steps employed up to the time of taking the sheet off of the roll 9 constitute what may be best described as a cold process.

I claim as my invention:

1. The method of manufacturing sheet packing material which comprises progressively superposing upon each other portions of a moist web consisting of clean asbestos fibres, impregnating the 1 portions while moist with latex during the step of superposing the said portions upon each other, pressing the impregnated superposed portions together to form a homogeneous sheet and to expel certain of the moisture therefrom, then subjecting the sheet thus formed to the effect of a drying heat.

2. The method of manufacturing sheet packing material which comprises continuously moving a preeprepared moist web made up of clean asbestos fibres between mating press rolls, superposing portions of the web while moist upon each other. impregnating said portions of the web while moist with latex during the step of superposing said portions upon each other, subjecting the portions thus impregnated to the action of pressure so as to produce a homogeneous sheet and to expel certain of the moisture therefrom, then subjecting the sheet thus formed to the action of a drying heat.

3. The method of manufacturing sheet packing material which comprises spirally winding a web of moist cleanly prepared asbestos fibres around a cylinder while progressively saturating the web while the fibrous constituent thereof is moist as it is wound about the cylinder. then removing the web thus impregnated from the cylinder, subjecting the web to the action of pressure so as to condense the wound portions thereof and produce a homogeneous sheet. and then subjecting the sheet thus formed to the action of a drying heat.

4. The process of manufacturing sheet packing material which consists in moving a moist web of cleanly prepared asbestos fibres over a traveling sieve so as to cause certain free moisture to escape therefrom. continuing the movement of the web while moist between press rolls so as to compress the web, superposing portions of the compressed web while moist upon each other while simultaneously saturating the portions with latex, subjecting the saturated superposed portions to the action of pressure so as to produce a homogeneous sheet, and then subjecting the 1 sheet to the action of a drying heat.

5. The method of manufacturing sheet packing material which comprises spirally winding about each other portions of a moist web of asbestos fibres, while simultaneously impregnating the moist web with latex, continuing the operation until a sheet of intended thickness is produced, subjecting the sheet to the action of pressure, then introducing the sheet to the effect of a treatment for eliminating the moisture therefrom.

6. The herein described method of manufacturing sheet packing material which consists in coiling a moist web of cleanly prepared asbestos fibres around a revolving cylinder so as to form thereon a plurality of wound portions thereof, coating one face of each wound portion of the web with latex during the coiling operation, bringing the coated face of one coiled portion into contact with an uncoated face of the next adjacent wound portion of the web while pressing same thereagainst, continuing the operation until a desired number of wound portions of the moist web are built up upon the cylinder, severing the coiled web from the cylinder to produce a flat sheet, subjecting the sheet to the action of pressure to compress the fibres and bond same to 1 the latex, removing the contained moisture from the sheet by the action of heat and then further subjecting the sheet to the effect of pressure to further condense same. RICHARD ROBERTS. 

